Method for the chemical beneficiation of berylite



3,295,962 METHOD FOR THE CHEMICAL BENEFICIATION F BERYLITE Wendell J. Biermann, Winnipeg, Manitoba, Canada, as-

signpr. to Beryloy Limited. (no personal liability),

Winnipeg,.Manit0ba, Canada Filed June 11, 1962, Ser. No. 201,710 1 Claim, (Cl. 75--115) .known .as berylite comprising chemically a double silicate of barium and beryllium. The beryllium contained in this ore, from 0.4 to 0.8% as. oxide, however, cannot be concentrated by conventional beneficiation methods and this the. .objectyof this invention to provide a beneficiation method which will successfully concentrate the berylliumin such ore.

In theetforts to find an effective beneficiation method for such ores, I first subjected the ore to concentrated acids at high temperatures. over extended times without effective or predictable beryllium extraction. During the courseof experimentation, however, I discovered that surprisingly the use of concentrated acids appeared to produce insoluble polynuclear compounds which blocked effective concentration, the formation of such insoluble compounds taking place at a time dependent upon the acidrconcentr-ation and temperature. Further investigation established that if the formation of such polynuclear compounds or complexescould be avoided by the proper selection of the parameters of acid concentration, temperature and time then effective beneficiation could be carried According to the invention therefor, effective beneficiation of berylite or other beryllium containing ore can be carried outby reacting such ore with an acid, for a time and .under temperature conditions dependent upon acid concentration.

The invention will be more fully understood with reference to. the following detailed description taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a graph illustrating the extraction of beryllium from berylite by means of diluted sulphuric acid with time under different temperature conditions.

FIGURE 2 is a graph similar to FIGURE 1 but showing the extraction of beryllium from berylite with concentrated sulphuric acid;

It istbelieved that the finely divided state in which the beryllium mineral occurs in berylite or similar ores precludes beneficiation by conventional beneficiation methods. In attempting to attackthe berylite-containing rock chemically, I subjected such mineralization to, in particular, sulphuricacid at high concentrations and high temperatures over extended periods of time.

The results were most disappointing in that at the end of the beneficiation process relatively low concentracted from 150 mesh sample of berylite-containing rock with time employing concentrated sulphuric acid in a nited States Patent 0 3,295,962 Patented Jan. 3, 1967 closed pressure vessel, it will be seen that there is a point in time of definite maximum extraction dependent on the temperature of the treated acid. For example, with the temperature of the sulphuric acid at 445 C. there is a very pronounced maximum percent extraction at an extracting time of approximately seven hours. After this point of maximum is reached then if the beneficiation process is continued there is a rapid fall off of beryllium concentration.

In the case where the acid is maintained at 350 C., the point of maximum extraction or concentration takes place slightly after the seven hours and the fall off concentration is not as steep as in the case of the hotter acid.

This phenomena which I discovered, and which so far as I am aware, was never previously discovered, was most unexpected showing what appears to be a solution of heryllium followed by reprecipitation in a very insoluble form at a somewhat lesser rate.

Experimental work was then carried out using beryllium oxide in place of the berylite-containing rock and I confirmed the above phenomena by observing that solutions of beryllium sulphate in sulphuric acid also threw down similar insoluble compounds 'when subjected to the same conditions of temperature as the original rock and sulphuric acid systems.

The only explanation which can be given to this be havior is that polynuclear sulphate-complexes, that is chainlike structures in which the beryllium ions are joined by one or more sulphate ions acting as bridges between them, are formed.

I do not believe that those skilled in the art have ever encountered such polynuclear sulphate complexes of beryllium but their existence is in accord with the fact that a maximum concentration of beryllium in solution is reached after a finite time.

It would follow that the polynuclear formation would be favoured by a high concentration of metal in solution and by a high concentration of the bridging species, namely, sulphuric acid. It occurred to me that both of these factors would be lowered by the addition of water with the result that there would be a likelihood that less reprecipitation of insoluble beryllium sulphates would take place if a somewhat diluted acid were used.

Following this deduction, experimental Work was carried out using a water solution containing by volume of concentrated sulphuric acid in the chemical beneficiation process.

As shown in FIGURE 1, the employment of the diluted sulphuric acid minimizes or eliminates the drop off of concentration with time confirming that the formation of the polynuclear sulphate complexes and their reprecipitation is substantially blocked. As before, the rate and degree of extraction or concentration of beryllium is increased with increasing temperature of the treating acid.

With reference to FIGURE 2, it will be seen that the concentration of the beryllium is increased with increasing temperature and the temperature range for optimum concentration has been found to be from approximately 350 to approximately 500 C., although even higher temperatures could be resorted to successfully, bearing in mind that for each temperature there is a definite limited time of beneficiation.

With reference to FIGURE 1, it will be seen that even at the lower temperature of 325 C. more effective extraction of the beryllium takes place where the acid is slightly diluted.

From the foregoing examples it will be apparent that effective chemical 'beneficiation of rock containing beryllium, for example, in the form known as berylite, can be chemically concentrated by treatment with hot concentrated acid at very high temperatures, for example,

3 350 to 500 C. or even higher, for limited times, the time becoming less at higher temperatures.

As analternative approach, such beneficiation can be eifected even more successfully at lower temperatures by using a slightly diluted acid.

The sulphuric acid solution involved in the process may be used as plant feed being suited as is to the solvent extraction system described in my \co-pending application Serial No. 199,663. Moreover, the sulphuric acid extract can be evaporated to dryness and ignited to form a solid oxide mixture, the evaporated sulphuric acid being recovered by absorption in conventional tower. The solid may be shipped, stored or sold as concentrate.

While I have given specific illustrations of my new beneficiation process, 'it will be understood that from these various detailed processes may be carried out without departing from the spirit of the invention or the scope of the appended claim.

What I claim is:

A method of concentrating beryllium in berylite ore comprising treating said ore with concentrated sulphuric acid at a temperature of approximately 350 C. to 500 C. for substantially 7 hours.

Mellor, Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol IV, Longmans, Green and 60., 1923, pp. 204-208.

DAVID L. RECK, Primary Examiner.

BENJAMIN HENKIN, Examiner.

H. W. CUMMINGS, N. F. MARKVA,

Assistant Examiners. 

